From: Takashi Yano <takashi.yano@nifty.ne.jp>
To: cygwin-developers@cygwin.com
Subject: Re: cygrunsrv + sshd + rsync = 20 times too slow -- throttled?
Date: Fri, 3 Sep 2021 21:22:05 +0900 [thread overview]
Message-ID: <20210903212205.acc2fc68cc4ffce9c1db3dd9@nifty.ne.jp> (raw)
In-Reply-To: <YTIJ+Sq/QeO7JlTB@calimero.vinschen.de>
[-- Attachment #1: Type: text/plain, Size: 3507 bytes --]
On Fri, 3 Sep 2021 13:41:45 +0200
Corinna Vinschen wrote:
> On Sep 3 13:31, Corinna Vinschen wrote:
> > On Sep 3 19:13, Takashi Yano wrote:
> > > On Fri, 3 Sep 2021 19:00:46 +0900
> > > Takashi Yano wrote:
> > > > On Thu, 2 Sep 2021 21:35:21 +0200
> > > > Corinna Vinschen wrote:
> > > > > On Sep 2 21:00, Corinna Vinschen wrote:
> > > > > It's getting too late again. I drop off for tonight, but I attached
> > > > > my POC code I have so far. It also adds the snippets from my previous
> > > > > patch which fixes stuff Takashi found during testing. It also fixes
> > > > > something which looks like a bug in raw_write:
> > > > >
> > > > > - ptr = ((char *) ptr) + chunk;
> > > > > + ptr = ((char *) ptr) + nbytes_now;
> > > > >
> > > > > Incrementing ptr by chunk bytes while only nbytes_now have been written
> > > > > looks incorrect.
> > > > >
> > > > > As for the reader, it makes the # of bytes to read dependent on the
> > > > > number of reader handles. I don't know if that's such a bright idea,
> > > > > but this can be changed easily.
> > > > >
> > > > > Anyway, this runs all my testcases successfully but they are anything
> > > > > but thorough.
> > > > >
> > > > > Patch relativ to topic/pipe attached. Would you both mind to take a
> > > > > scrutinizing look?
> > > >
> > > > Thanks.
> > > >
> > > > Your code seems that read() returns only the partial data even
> > > > if the pipe stil has more data. Is this by design?
> > > >
> > > > This happes in both blocking and non-blocking case.
> > >
> > > The patch attached seems to fix the issue.
> >
> > I'm sorry, but I don't see what your patch is supposed to do in the
> > first place. What I see is that it now calls NtQueryInformationFile
> > even in the non-blocking case, which is not supposed to happen.
> >
> > I'm a bit puzzled what the actual bug is.
> >
> > The code changing len is only called if there's no data in the pipe.
> > In that case we only request a partial buffer so as not to block
> > the writer on select.
> >
> > If there *is* data in the pipe, it will just go straight to the
> > NtReadFile code without changing len.
> >
> > Where's the mistake?
>
> Oh, wait. Do you mean, if we only request less than len bytes, but
> after NtReadFile there's still data in the buffer, we should try to
> deplete the buffer up to len bytes in a subsequent NtReadFile?
Yes. I am sorry, my intent was not clear because I did more than
necessary in the previous patch. Please see attached patch revised.
> I thought this is unnecessary, actually, because of POSIX:
>
> The standard developers considered adding atomicity requirements to a
> pipe or FIFO, but recognized that due to the nature of pipes and FIFOs
> there could be no guarantee of atomicity of reads of {PIPE_BUF} or any
> other size that would be an aid to applications portability.
POSIX says:
The value returned may be less than nbyte if the number of bytes left
in the file is less than nbyte, if the read() request was interrupted
by a signal, or if the file is a pipe or FIFO or special file and has
~~~
fewer than nbyte bytes immediately available for reading.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
https://pubs.opengroup.org/onlinepubs/009604599/functions/read.html
If it is turned over, read() should read all data immediately available,
I think.
--
Takashi Yano <takashi.yano@nifty.ne.jp>
[-- Attachment #2: pipe-corinna4-fix.patch --]
[-- Type: application/octet-stream, Size: 2301 bytes --]
diff --git a/winsup/cygwin/fhandler_pipe.cc b/winsup/cygwin/fhandler_pipe.cc
index 85730d039..ef7823ae5 100644
--- a/winsup/cygwin/fhandler_pipe.cc
+++ b/winsup/cygwin/fhandler_pipe.cc
@@ -222,6 +222,7 @@ fhandler_pipe::raw_read (void *ptr, size_t& len)
DWORD waitret = WAIT_OBJECT_0;
bool keep_looping = false;
size_t orig_len = len;
+ size_t total_len = 0;
if (!len)
return;
@@ -236,7 +237,8 @@ fhandler_pipe::raw_read (void *ptr, size_t& len)
do
{
- len = orig_len;
+ char *ptr1 = (char *) ptr + total_len;
+ len = orig_len - total_len;
keep_looping = false;
if (evt)
ResetEvent (evt);
@@ -260,6 +262,12 @@ fhandler_pipe::raw_read (void *ptr, size_t& len)
FilePipeLocalInformation);
if (NT_SUCCESS (status) && fpli.ReadDataAvailable == 0)
{
+ if (total_len != 0)
+ {
+ len = total_len;
+ ReleaseMutex (read_mtx);
+ break;
+ }
reader_count = get_obj_handle_count (get_handle ());
if (reader_count < 10)
max_len = fpli.InboundQuota / (2 * reader_count);
@@ -267,7 +275,7 @@ fhandler_pipe::raw_read (void *ptr, size_t& len)
len = max_len;
}
}
- status = NtReadFile (get_handle (), evt, NULL, NULL, &io, ptr,
+ status = NtReadFile (get_handle (), evt, NULL, NULL, &io, ptr1,
len, NULL, NULL);
if (!is_nonblocking ())
ReleaseMutex (read_mtx);
@@ -291,9 +299,13 @@ fhandler_pipe::raw_read (void *ptr, size_t& len)
}
else if (NT_SUCCESS (status))
{
- len = io.Information;
- if (len == 0)
+ if (io.Information == 0)
keep_looping = true;
+ total_len += io.Information;
+ if (!is_nonblocking () && total_len < orig_len)
+ keep_looping = true;
+ else
+ len = total_len;
}
else
{
@@ -308,9 +320,13 @@ fhandler_pipe::raw_read (void *ptr, size_t& len)
case STATUS_MORE_ENTRIES:
case STATUS_BUFFER_OVERFLOW:
/* `io.Information' is supposedly valid. */
- len = io.Information;
- if (len == 0)
+ if (io.Information == 0)
+ keep_looping = true;
+ total_len += io.Information;
+ if (!is_nonblocking () && total_len < orig_len)
keep_looping = true;
+ else
+ len = total_len;
break;
case STATUS_PIPE_LISTENING:
case STATUS_PIPE_EMPTY:
next prev parent reply other threads:[~2021-09-03 12:22 UTC|newest]
Thread overview: 250+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <41A583E1-C8E7-42AB-9F24-EEC33A41EC60@house.org>
[not found] ` <20210825201845.07b6400b79dc5558a7761efe@nifty.ne.jp>
[not found] ` <f8106fe7-a2b8-d106-3061-4d888124f4b0@cornell.edu>
[not found] ` <20210826062934.54f2f2216021c095bb7ba13b@nifty.ne.jp>
[not found] ` <d0a8c57d-1ed1-6b4f-c6e7-cbe0e2ec8a1c@cornell.edu>
[not found] ` <3b560051-ab27-f392-ca4b-d1fd9b5733b0@cornell.edu>
[not found] ` <20210827202440.47706fc2fc07c5e9a1bc0047@nifty.ne.jp>
[not found] ` <4f2cb5f3-ce9c-c617-f65f-841a5eca096e@cornell.edu>
[not found] ` <20210828022111.91ef5b4ff24f6da9fadb489e@nifty.ne.jp>
[not found] ` <YSn3L0W1M527utK0@calimero.vinschen.de>
[not found] ` <20210828184102.f2206a8a9e5fe5cf24bf5e45@nifty.ne.jp>
[not found] ` <YSok0PoCQn2TPPrn@calimero.vinschen.de>
[not found] ` <20210829004346.c2f80469abc3a07fd4b2918d@nifty.ne.jp>
[not found] ` <e8caa02f-be85-33bc-3f09-347c1cdb0923@cornell.edu>
[not found] ` <20210829174124.0c1ae6c16a3e8da1f490abc7@nifty.ne.jp>
[not found] ` <6e9bb35e-6f4f-cf78-e515-549da487b5ef@cornell.edu>
2021-08-30 7:57 ` Corinna Vinschen
[not found] ` <20210829180729.48b4e877f773cb3980c5766d@nifty.ne.jp>
[not found] ` <789f056a-f164-d71d-1dc9-230f5a41846d@cornell.edu>
2021-08-30 8:27 ` Corinna Vinschen
2021-08-30 13:00 ` Corinna Vinschen
2021-08-30 13:20 ` Corinna Vinschen
2021-08-30 13:41 ` Ken Brown
2021-08-30 14:12 ` Corinna Vinschen
2021-08-30 14:52 ` Ken Brown
2021-08-30 15:15 ` Corinna Vinschen
[not found] ` <20210830043756.8aa0ada77db0bfbbe3889f62@nifty.ne.jp>
[not found] ` <47e5dd74-b940-f305-fd5a-c6c9d8f41305@cornell.edu>
2021-08-30 8:48 ` Corinna Vinschen
[not found] ` <c62d18df-ab7a-7233-62ee-29a8eced5353@cornell.edu>
[not found] ` <20210830091314.f9a2cb71794d0f68cdb5eba7@nifty.ne.jp>
[not found] ` <20210830092259.52f7d54fc3fa340738373af4@nifty.ne.jp>
[not found] ` <d217ef03-7858-5e22-0aa6-f0507eedd9da@cornell.edu>
[not found] ` <20210830170204.fa91eaf110f310f13b67abc3@nifty.ne.jp>
2021-08-30 10:20 ` Corinna Vinschen
2021-08-30 10:38 ` Corinna Vinschen
2021-08-30 12:04 ` Takashi Yano
2021-08-30 12:55 ` Corinna Vinschen
2021-08-30 13:31 ` Corinna Vinschen
2021-08-31 8:50 ` Takashi Yano
2021-08-30 13:51 ` Ken Brown
2021-08-30 15:00 ` Ken Brown
2021-08-30 15:19 ` Corinna Vinschen
2021-08-30 15:43 ` Ken Brown
2021-08-31 9:43 ` Corinna Vinschen
2021-08-31 8:52 ` Takashi Yano
2021-08-31 9:04 ` Corinna Vinschen
2021-08-31 11:05 ` Takashi Yano
2021-08-31 15:20 ` Corinna Vinschen
2021-09-01 2:39 ` Takashi Yano
2021-09-01 8:03 ` Corinna Vinschen
2021-09-01 8:13 ` Corinna Vinschen
2021-08-30 13:36 ` Ken Brown
2021-08-30 14:05 ` Corinna Vinschen
2021-08-30 15:53 ` Corinna Vinschen
2021-08-30 17:00 ` Corinna Vinschen
2021-08-30 17:11 ` Corinna Vinschen
2021-08-30 18:59 ` Ken Brown
2021-08-30 19:12 ` Ken Brown
2021-08-30 20:21 ` Corinna Vinschen
2021-08-30 20:14 ` Corinna Vinschen
2021-08-30 20:47 ` Ken Brown
2021-08-31 8:55 ` Takashi Yano
2021-08-31 9:08 ` Corinna Vinschen
2021-08-31 9:25 ` Takashi Yano
2021-08-31 10:05 ` Corinna Vinschen
2021-08-31 10:18 ` Corinna Vinschen
2021-08-31 11:45 ` Takashi Yano
2021-08-31 12:31 ` Takashi Yano
2021-08-31 15:08 ` Corinna Vinschen
2021-08-31 12:33 ` Ken Brown
2021-08-31 15:18 ` Corinna Vinschen
2021-08-31 15:27 ` Corinna Vinschen
2021-08-31 15:50 ` Corinna Vinschen
2021-08-31 16:19 ` Ken Brown
2021-08-31 16:38 ` Ken Brown
2021-08-31 17:30 ` Corinna Vinschen
2021-08-31 18:54 ` Ken Brown
2021-08-31 19:51 ` Corinna Vinschen
2021-08-31 23:02 ` Takashi Yano
2021-09-01 0:16 ` Takashi Yano
2021-09-01 8:07 ` Corinna Vinschen
2021-09-01 8:23 ` Takashi Yano
2021-09-01 8:46 ` Corinna Vinschen
2021-09-01 12:56 ` Ken Brown
2021-09-01 13:52 ` Corinna Vinschen
2021-09-01 23:02 ` Ken Brown
2021-09-02 8:17 ` Corinna Vinschen
2021-09-02 13:01 ` Ken Brown
2021-09-02 19:00 ` Corinna Vinschen
2021-09-02 19:34 ` Ken Brown
2021-09-02 19:35 ` Corinna Vinschen
2021-09-02 20:19 ` Ken Brown
2021-09-03 9:12 ` Corinna Vinschen
2021-09-03 19:00 ` Ken Brown
2021-09-03 19:53 ` Ken Brown
2021-09-03 19:54 ` Corinna Vinschen
2021-09-03 20:05 ` Ken Brown
2021-09-03 10:00 ` Takashi Yano
2021-09-03 10:13 ` Takashi Yano
2021-09-03 11:31 ` Corinna Vinschen
2021-09-03 11:41 ` Corinna Vinschen
2021-09-03 12:13 ` Ken Brown
2021-09-03 15:00 ` Corinna Vinschen
2021-09-03 15:14 ` Ken Brown
2021-09-03 15:17 ` Corinna Vinschen
2021-09-03 12:22 ` Takashi Yano [this message]
2021-09-03 13:27 ` Ken Brown
2021-09-03 15:37 ` Corinna Vinschen
2021-09-04 12:02 ` Takashi Yano
2021-09-04 12:37 ` Takashi Yano
2021-09-04 14:04 ` Ken Brown
2021-09-04 23:15 ` Takashi Yano
2021-09-05 13:40 ` Takashi Yano
2021-09-05 13:50 ` Takashi Yano
2021-09-05 18:47 ` Ken Brown
2021-09-05 19:42 ` Takashi Yano
2021-09-05 20:09 ` Takashi Yano
2021-09-05 20:27 ` Ken Brown
2021-09-06 8:13 ` Corinna Vinschen
2021-09-06 11:16 ` Takashi Yano
2021-09-06 12:49 ` Corinna Vinschen
2021-09-06 13:16 ` Takashi Yano
2021-09-06 16:08 ` Corinna Vinschen
2021-09-06 23:39 ` Takashi Yano
2021-09-07 9:14 ` Corinna Vinschen
2021-09-07 11:03 ` Takashi Yano
2021-09-07 16:14 ` Ken Brown
2021-09-07 18:26 ` Corinna Vinschen
2021-09-03 10:38 ` Takashi Yano
2021-09-08 11:32 ` Takashi Yano
2021-09-08 11:55 ` Corinna Vinschen
2021-09-08 12:33 ` Takashi Yano
2021-09-08 17:43 ` Ken Brown
2021-09-08 18:28 ` Corinna Vinschen
2021-09-02 8:15 ` Takashi Yano
2021-09-02 18:54 ` Corinna Vinschen
2021-09-07 3:26 ` Takashi Yano
2021-09-07 10:50 ` Takashi Yano
2021-09-08 0:07 ` Takashi Yano
2021-09-08 4:11 ` Takashi Yano
2021-09-08 9:01 ` Takashi Yano
2021-09-08 9:01 ` Corinna Vinschen
2021-09-08 9:26 ` Corinna Vinschen
2021-09-08 9:45 ` Takashi Yano
2021-09-08 10:04 ` Corinna Vinschen
2021-09-08 10:45 ` Takashi Yano
2021-09-08 10:51 ` Corinna Vinschen
2021-09-09 3:21 ` Takashi Yano
2021-09-09 9:37 ` Corinna Vinschen
2021-09-09 10:55 ` Takashi Yano
2021-09-09 11:41 ` Corinna Vinschen
2021-09-08 9:37 ` Takashi Yano
2021-09-09 3:41 ` Takashi Yano
2021-09-09 8:05 ` Takashi Yano
2021-09-09 12:19 ` Takashi Yano
2021-09-09 12:42 ` Takashi Yano
2021-09-09 21:53 ` Takashi Yano
2021-09-10 3:41 ` Takashi Yano
2021-09-10 10:57 ` Ken Brown
2021-09-10 15:17 ` Ken Brown
2021-09-10 15:26 ` Corinna Vinschen
2021-09-10 22:57 ` Takashi Yano
2021-09-11 2:17 ` Ken Brown
2021-09-11 2:35 ` Takashi Yano
2021-09-11 13:12 ` Ken Brown
2021-09-12 6:23 ` Takashi Yano
2021-09-12 14:39 ` Ken Brown
2021-09-13 9:11 ` Corinna Vinschen
2021-09-13 12:30 ` Ken Brown
2021-09-12 8:48 ` Takashi Yano
2021-09-12 11:04 ` Takashi Yano
2021-09-12 15:10 ` Ken Brown
2021-09-12 21:46 ` Ken Brown
2021-09-12 23:54 ` Takashi Yano
2021-09-13 2:19 ` Ken Brown
2021-09-13 8:40 ` Takashi Yano
2021-09-13 12:51 ` Ken Brown
2021-09-13 17:05 ` Ken Brown
2021-09-13 9:42 ` Corinna Vinschen
2021-09-13 13:03 ` Ken Brown
2021-09-13 18:39 ` Takashi Yano
2021-09-12 23:41 ` Takashi Yano
2021-09-13 17:42 ` Ken Brown
2021-09-13 18:54 ` Takashi Yano
2021-09-13 18:32 ` Corinna Vinschen
2021-09-13 19:37 ` Takashi Yano
2021-09-13 20:15 ` Corinna Vinschen
2021-09-14 8:07 ` Takashi Yano
2021-09-14 8:47 ` Corinna Vinschen
2021-09-14 12:38 ` Ken Brown
2021-09-14 14:15 ` Corinna Vinschen
2021-09-14 8:08 ` Takashi Yano
2021-09-14 9:03 ` Corinna Vinschen
2021-09-14 9:56 ` Takashi Yano
2021-09-14 10:19 ` Takashi Yano
2021-09-14 11:03 ` Corinna Vinschen
2021-09-14 12:05 ` Takashi Yano
2021-09-14 14:17 ` Corinna Vinschen
2021-09-14 22:14 ` Ken Brown
2021-09-15 0:21 ` Takashi Yano
2021-09-15 0:44 ` Takashi Yano
2021-09-15 0:59 ` Takashi Yano
2021-09-15 9:57 ` Corinna Vinschen
2021-09-15 10:48 ` Takashi Yano
2021-09-15 10:58 ` Takashi Yano
2021-09-15 11:34 ` Corinna Vinschen
2021-09-15 11:40 ` Corinna Vinschen
2021-09-15 11:13 ` Corinna Vinschen
2021-09-15 11:41 ` Ken Brown
2021-09-15 11:49 ` Corinna Vinschen
2021-09-15 11:54 ` Takashi Yano
2021-09-15 12:20 ` Corinna Vinschen
2021-09-15 13:04 ` Takashi Yano
2021-09-15 13:42 ` Corinna Vinschen
2021-09-15 16:22 ` Ken Brown
2021-09-15 17:09 ` Ken Brown
2021-09-16 0:22 ` Takashi Yano
2021-09-16 2:28 ` Ken Brown
2021-09-16 9:09 ` Takashi Yano
2021-09-16 13:02 ` Takashi Yano
2021-09-16 13:25 ` Corinna Vinschen
2021-09-16 14:27 ` Takashi Yano
2021-09-16 15:01 ` Corinna Vinschen
2021-09-16 15:46 ` Ken Brown
2021-09-16 16:02 ` Ken Brown
2021-09-16 19:42 ` Takashi Yano
2021-09-16 20:28 ` Ken Brown
2021-09-16 19:48 ` Ken Brown
2021-09-16 20:01 ` Takashi Yano
2021-09-17 2:25 ` Ken Brown
2021-09-17 8:31 ` Takashi Yano
2021-09-17 11:16 ` Ken Brown
2021-09-17 16:23 ` Takashi Yano
2021-09-17 17:08 ` Ken Brown
2021-09-17 17:39 ` Jon Turney
2021-09-17 17:43 ` Takashi Yano
2021-09-17 19:53 ` Ken Brown
2021-09-18 1:30 ` Takashi Yano
2021-09-18 2:07 ` Ken Brown
2021-09-18 2:10 ` Ken Brown
2021-09-18 8:03 ` Takashi Yano
2021-09-18 11:12 ` Ken Brown
2021-09-18 11:35 ` Takashi Yano
2021-09-18 14:11 ` Jon Turney
2021-09-18 13:44 ` Ken Brown
2021-09-19 1:31 ` Takashi Yano
2021-09-19 14:35 ` Ken Brown
2021-09-20 9:29 ` Takashi Yano
2021-09-16 0:13 ` Takashi Yano
2021-09-16 2:26 ` Ken Brown
2021-09-13 9:07 ` Corinna Vinschen
2021-09-20 12:52 ` Takashi Yano
2021-09-20 19:14 ` Ken Brown
2021-09-20 21:09 ` Ken Brown
2021-09-20 21:21 ` Ken Brown
2021-09-20 21:27 ` Takashi Yano
2021-09-20 21:39 ` Ken Brown
2021-09-20 22:16 ` Takashi Yano
2021-09-20 22:46 ` Ken Brown
2021-09-20 22:50 ` Ken Brown
2021-09-20 23:22 ` Takashi Yano
2021-09-21 8:30 ` Takashi Yano
2021-09-21 9:26 ` Mark Geisert
2021-09-21 10:10 ` Takashi Yano
2021-09-21 21:10 ` Mark Geisert
2021-09-21 13:31 ` Ken Brown
2021-09-21 15:36 ` Takashi Yano
2021-09-21 18:51 ` Ken Brown
2021-09-23 8:26 ` Takashi Yano
2021-09-23 13:03 ` Ken Brown
2021-09-23 15:03 ` Takashi Yano
2021-09-23 16:29 ` Ken Brown
2021-10-18 10:51 ` Corinna Vinschen
2021-10-18 12:02 ` Takashi Yano
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